A trio of theoretical physicists at the Pennsylvania State University has calculated the upper limit for the possible quantization of time—they suggest 10−33 seconds as the upper limit for the period of a universal oscillator. In their paper published in the journal Physical Review Letters, Garrett Wendel, Luis Martínez and Martin Bojowald outline their theory and suggest a possible way to prove it.
Source:
https://phys.org/news/2020-06-theorists-upper-limit-quantization.html